Upcyling / Recycling an Old Stereo Amplifier - Chapter 2

Upcyling / Recycling an Old Stereo Amplifier - Chapter 2 - Intro

In chapter 1 we saw me taking apart a 20 year old system I knew nothing about and trying to retrofit new components (which I knew nothing about), with some exciting but disastrous results.

Summary: Unless you spend some hours looking at you old and new parts and really understanding what things do then you will likely not succeed.

Cheap class D amplifier boards are quite reliable for building active portable speakers, where a casing is wood or plastic, and the amplifier is always attached to the speaker. I have done this 3 or 4 times with no problems. But building a amplifier, has proven far more vexing.

Upcyling / Recycling an Old Stereo Amplifier - Reusing an Old Power Supply

Even the title of this section underlines my ignorance. I measured output voltages from the old transformer only, and as such there were many unknowns. Although a power supply may supply 12V or 24V what current can it support?

Upcyling / Recycling an Old Stereo Amplifier - Speaker Terminals

Although there were eight wires leading to my 8 speaker terminals, some were bridged. This created a short circuit when I used them with my modern Class D amplifier which cannot (i liveable) have shared grounds. 

Upcyling / Recycling an Old Stereo Amplifier - Un-Painted Metal Cased

For a beginner a plastic or perhaps wooden case is more forgiving than a metal case. A dropped wire, or a miss-placed screw can create all sorts of problems. 

Upcyling / Recycling an Old Stereo Amplifier - Conclusion

If you really understand electronics then it may be possible to reuse some of the old components out of an old amplifier. The less you understand the more you should disassemble. 

For example a capacitor pulled from a boards will likley behave predictably as per specs printed on side. But. . . .

A module such as speaker terminals module with PCB may hide surprises that you can so without! 

So in ultimate summary reusing base components is less likely to get you in to trouble than trying to fit new modules in with older modules, they may not "play" nicely. 

Lastly I had some help with this project from folks over at DIY Audio Forum.  So thanks for that guys. Link to post below:

TPA 3116 Boom!

Other links not related to this post:

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Environmental Permit Applications

Numo S10 Review

Numo S10 Review - Intro

My iphone took a dip in the sea recently. Dead. £700 for a iphone X (£60 a month with Vodafone). So I took a punt on a Numo S10 for £100 from Amazon. Findings below:

Numo S10 Review - Screen

I can find no difference between the screen on this Numo S10 and my iPhone 6s. It is a clear screen, sensitive to the touch, I have no problems with it.

Screen is Perfectly Adequate in Size and Quality

Numo S10 Review - Buttons

There are volume buttons and a power button. . . and that it. They are stiff to operate but I like that. I should imagine it would annoy some people though. The rubbery feel is quite nice. I have no problems with the buttons on the S10. 

Buttons are Heavy but have a Quality Feel

Numo S10 Review - Performance

Snappy! Lag free Android experience, works A OK. Loads apps in a snap. The Numo S10 has a quad core processor, and 2GB of RAM. I haven't done any gaming on it but its seems fine. I have no problems with the performance on the Numo S10. 

Numo S10 Review - Port Covers / Flaps

Oh Numu! It was going sooooo well. These port flaps were obviously designed last thing on a Friday. There are 3 in total that cover:

• Charging Port
• SIM / SD Card Port
• Ear Phone Port

The biggest faff is the charging port, it is hard to get the slim fit micro USB connector to fit in the port, without put the port cover / flap in the exact right position. Its very annoying. 

Add caption

Dual Sim or Sim & Micro SD . . . handy!

Deep Recess and Annoying Falp Make Plugging in Ear Phone  Bit Tricky

Charging. . . . 

. . . again Wrestle with the Flap / Cover in order to Plug in Cahrger

Numo S10 Review - Conclusions

A good value android phone, supposedly water proof, quick performer, excellent screen and build quality. . . apart from the port cover / ports flaps which let it down somewhat.

Would I recommend. . . not sure. It price is a big plus point.

The port flaps on an Otter Box Armour are fine to use despite being large and chunky. Here we have a nicley implemented phone, let down at the last minutes by overly small and fiddly port covers. 

Oh no Google Pay. . . which would have been handy. Lack of NFC assures this.

Close Up of Moulding

Pencil for Scale

Rear of Phone - I like the colour Orange!

Fire Prevention Plan

Waste Transfer Station Permit

Illustrator Devon

Upcyling / Recycling an Old Stereo Amplifier

Upcyling / Recycling an Old Stereo Amplifier - Chapter 1 - Intro

I am not overly interested in electronics I find it fiddly and not very satisfying. However, to me throwing a large complicated piece of electronic equipment in the bin is a literally a crime. . .  or it soon will be. E Waste in Ghana

For someone with low skills such as myself the percentage of what can be upcycled / reused is fairly low. But it saves some waste at least. It may also save you some money, by re-using the case, power supply and connectors you are perhaps saving £50 / $100 on a DIY build. . . . . . I hope to complete this project for about £20 / $40. Bear in mind you can buy a cheaper amplifier for £30! But where is the fun / satisfaction in that I ask. . . . .

Watch Chapter 1 You Tube Video on Upcycling an Amplifier. 

I should point out that my first attempt at this build went horribly wrong. I did not understand the power supply and some of the other wiring. I fried all of my new circuits! So more rubbish for the scrap heap! So you know where you stand perhaps use a modern switching power supply. . . but then our goal to prevent waste is very much reduced. I am only really reusing the case, and a few connectors. Hardly worth the effort. 

Upcyling / Recycling an Old Stereo Amplifier - Chapter 1- What You Need

A minimum kit list of attempting this project is:

• Voltmeter / Multi-meter
• Soldering Iron
• Screw Driver 
• Wire
• Replacement Circuit Board with Suitable Voltage

Upcyling / Recycling an Old Stereo Amplifier - Chapter 1 - Whats Inside?

The below amplifier is an old friend I bought this when I was 18 (over 20 yeas ago) and it has been used for countless parties, outdoor raves (linked with friends amplifiers), run on generators, used as a seat at bus stops. . . . . hence dent in lid! But alas it no longer works, and having checked the side I found the circuit board had a large crack running through it, and some of the leg have been torn from one of the large Class A Amplifiers.

WARNING: On the back of you amplifier there will likely be a message saying "Danger of Death" or "Risk of Electric Shock". This is there because there are bits inside that will kill you if you touch them. So if you do take the lid off you amplifier, that is what might happen. I am just explaining what I did. Only copy me if YOU choose to do so. 

So next I took off the lid, and had a look inside and found the following (click to enlarge):

You will note the large brown circuit board that cover most of the inside of this amplifier. I have no idea how to repair this, so will be replacing this with a small circuit board purchased from eBay. The boards look like this:

There are lots to choose from I will deal with which one later in this post. I am using the TPA3116. As I have some past experience with this board.

Upcyling / Recycling an Old Stereo Amplifier - Chapter 1 - Which Bits to Keep

So after removing all of the bits you do not need you will end up with this (click to enlarge):

I have removed the large heat sink because I am using a Class D Amplifier so  I will not need the large heat sink, if you are choosing a Class A or Class AB amplifier then it would be a bonus to reuse your heat sink. 

A good quality power supply will cost quite a lot, so the one you have is worth keeping. The power supply might be AC rather then DC current, check this with a multi meter. If it is Look out for the bridge rectifiers and keep those too so you can make DC current for new amplifier board! 

This power supply gives out multiple voltages, which is very handy. I suspect most amplifiers will have this arrangements as they will need to power low voltage lighting and higher voltage amplifier chips. The voltages from this supply are "non" standard. They are not 12, 24, 36 etc. they are 17, 27 43 etc. thye go up to 93V so risk of a shock there if I am not careful!

Also the RCA inputs and Output Terminals and any other input / out put parts might be worth keeping. There were also some large capacitors, which may come in handy for decoupling.  

Upcyling / Recycling an Old Stereo Amplifier - Chapter 1 - Watch a Video Summary

I have tried to summaries findings in Chapter 2. . . although for a full description of what went wrong perhaps head over to DIY Audio. 

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